Respiratory system References Crystal phase composition (particle size in nm) Type of exposure Type and number of animals Results Takenaka et al., 1986 [52 ] Anatase TiO2 (15–40) Inhalation: aerosols of 8.6 mg/m3 TiO2 for 7 hr/day, 5 day/wk for up to 1 year.24 female Wistar rats Lung burden: TiO2 was found in macrophages and in the perivascular spaces. Ferin et al., 1992 [53 ] Rutile TiO2 (12; 230) 2 (21; 250) Intratracheal instillation : all TiO2 : 500 μ g; 21 nm TiO2 : 65–1000 μ g/rat; 250 nm TiO2 : 1000 μ g/rat. Inhalation:
2
3
.
5
±
3
.
2
mg/m3 21 nm TiO2 ;
2
3
.
0
±
4
.
1
mg/m3 250 nm TiO2 for 6 h/day, 5 day/wk for up to 12 wks.Instillation study : 4–8 male Fischer 344 rats Inhalation study: 4 male Fischer 344 rats per group.Instillation study : unlavagable lung burden decreased from 12 nm to 250 nm particles. Inhalation study : greater 21 nm TiO2 NP concentration in the interstitium, epithelial cells, and alveolar space.Basic intratracheal instillation: 500 μ g of 250 and 20 nm TiO2 .Basic instillation: 4 male Fischer 344 rats per group.Basic instillation: higher lung retained amount and greater inflammatory response in the 20 nm TiO2 NP treatment.Oberdorster et al., 1992 [54 ] Anatase TiO2 (~20; ~250) 2 (~12; ~220) Intratracheal reinstillation:
1
0
4
±
8
μ g 20 nm free TiO2 ,
1
0
4
±
1
0
μ g, 20 nm TiO2 phagocitized by AMs, 100 μ g serum coated particles,
6
.
8
×
1
0
6
AMs,
2
.
2
×
1
0
6
PMNs.Reinstillation: 4–10 male Fischer 344 rats per group.Reinstillation: greater amount of free particles retained in lavaged lungs.Intratracheal dose -response: 500, 1000 μ g 250 nm TiO2 ; 65–1000 μ g 20 nm TiO2 ; 500 μ g 220 nm TiO2 ; 500 μ g 12 nm TiO2 .Dose-response: 20 nm TiO2 NPs caused a dose-dependent PMN lung influx. Oberdorster et al., 1994 [55 ] Anatase TiO2 (20; 250) Inhalation: aerosols of
2
3
.
5
±
2
.
9
mg/m3 20 nm TiO2 and
2
2
.
3
±
4
.
2
mg/m3 250 nm TiO2 for 6 hr/day, 5 day/wk for up to 12 wks.64 male Fischer 344 rats Inflammatory action: AMs, PMNs, TPC increased in BAL. Pulmonary retention : increased after 20 nm TiO2 . Histology: lung fibrosis after 20 nm TiO2 . Heinreich et al., 1995 [56 ] P25 Degussa TiO2 (15–40) Inhalation: 10 mg/m3 TiO2 for 18 hr a day for 24 (rats) and 13.5 (mice) months.100 female Wistar rats 80 NMRI mice Rats: adenocarcinomas, squamous cell carcinomas, adenomas increased. Mice: no differences in tumor rates. Baggs et al., 1997 [57 ] Pigment-grade TiO2 (250) 2 (20) Inhalation: aerosols of 22.3 mg/m3 of 250 nm TiO2 and 23.5 mg/m3 of 20 nm TiO2 for 6 hr/day, 5 day/wk for up to 12 wks.3-4 male Fischer 344 rats per group Histology: alveolar epithelial thickness and septal fibrosis after both TiO2 treatments. Zhang et al., 1998 [58 ] TiO2 (28) Intratracheal instillation : 1 mg TiO2 .4–6 male Wistar rats per group Inflammatory action: TCC, NEUs, AMs, TPC, and LDH increased in BAL. Afaq et al., 1998 [59 ] TiO2 (30) Intratracheal instillation : 2 mg TiO2 per animal.6 female Albino rats per group Inflammatory action: AMs, ACP, and LDH increased in BAL. Oxidative stress: LPO and antioxidant activities increasedOberdorster et al., 2000 [60 ] TiO2 (20; 250) Intratracheal instillation : no more detailedRats Mice Inflammatory action: NEUs increased after 20 nm TiO2 . Höhr et al., 2002 [61 ] Native or methylated TiO2 (20–30; 180) Intratracheal instillation : equivalent mass (1 or 6 mg) and surface doses (100, 500, 600 and 3000 cm2 ) of TiO2 per animal.5 female Wistar rats per group Inflammatory action: native TiO2 NPs increased TCC, PMNs, TPC, ALP, LDH, GGT, NAG and β glucuronidase in BAL. Bermudez et al., 2004 [49 ] P25 Degussa TiO2 (21) Inhalation: aerosols of 0.5–10 mg/m3 TiO2 for 6 hr/day, 5 days/week, for 13 weeks.Groups of 25 animals for each species: Female 3C3F1/CrlBR mice; CDF (F344)/CrlBR rats; Lak:LVG (SYR) BR hamsters. Lung burdens: equivalent in rats and mice, lower in hamsters. Inflammatory action: increase in TCC, AMs, NEUs, LYMs (rats and mice); TPC and LDH in BAL (rats); only NEUs in hamsters; Histology: terminal bronchiolar and alveolar cell replication. Renwick et al., 2004 [62 ] TiO2 (29; 250) Intratracheal instillation : 125, 500 μ g TiO2 .Male Wistar rats Inflammatory action: NEUs, GGT, TPC, LDH increased after 29 nm TiO2 in BAL. AM phagocytotic ability : decreased. Warheit et al., 2006 [39 ] Rutile pigment grade TiO2 (300) 2 rods (length: 92–233; wide: 20–35) 2 dots (5.8–6.1) Intratracheal instillation : 1, 5 mg/kg TiO2 .5 male Crl:CD(SD)IGS BR rats per group Inflammatory action: increase in NEUs (all particles) and LDH (TiO2 rods). Histology: TiO2 -containing aggregated macrophages in lung (all particles). Warheit et al., 2007 [44 , 45 ] ~98% rutile TiO2 , 2% alumina (~100) 2 , ~7 wt% amorphous silica, ~5 wt% alumina (~100) 2 (~25) 2 , ~1% alumina (382 in water) Intratrachel instillation: 1, 5 mg/kg TiO2 .4-5 male Crl:CD(SD)IGS BR rats per group Inflammatory action: NEUs, LDH, and microprotein increased in BAL by P25 TiO2 Cell proliferation: airway and lung parenchymal cells proliferation increased after P25 TiO2 . Histology: AM accumulation with tissue thickening after P25 TiO2 . Chen et al., 2006 [42 ] Rutile TiO2 (21) 2 (180–250) Intratracheal instillation : 0.1, 0.5 mg TiO2 .6 male ICR mice per group Lung morphology: emphysematous change and alveolar epithelial thickness after 21 nm TiO2 NPs. Apoptosis: increased in AMs and PNEs. Grassian et al., 2007 [41 ] Anatase TiO2 (3.5 ± 1.0) Inhalation: aerosols of 0.77, 7.22 mg/m3 TiO2 for 4 hr (acute exposure); and
8
.
8
8
±
1
.
9
8
mg/m3 TiO2 for 4 hr/day for 10 days (subacute exposure).6 male C57Bl/6 mice per group Acute exposure: TCC and AMs increased in BAL. Subacute exposure: AMs increased in BAL. Li et al., 2007 [35 ] Anatase TiO2 (3) 2 (20) Intratracheal instillation : 0.4–40 mg/kg TiO2 .5 Male Kunming mice per group BAL biochemical parameters: TPC, ALB, ALP, and ACP increased by both TiO2 . Histology: alveolar wall thickening and destruction. Geiser et al., 2005 [63 ] TiO2 (4) Inhalation: 10 rats were exposed to 0.11 mg/m3 TiO2 aerosols for 1 hr.10 male WKY/NCrl BR rats TiO2 distribution: luminal side of airways/alveoli (79.3%), epithelial or endothelial cells (4.6%), connective tissue (4.8%), capillaries (11.3%).Mühlfeld et al., 2007 [64 ] See Geiser et al., 2005 [63 ] TiO2 distribution: connective tissue and the capillary lumen were the preferential target of NPs at 1 and 24 hr, respectively. Nemmar et al., 2008 [43 ] Rutile TiO2 nanorods (4–6) Intratracheal instillation : 1, 5 mg/kg TiO2 6-7 male Wistar rats per group Inflammatory action: AMs, PMNs increased in BAL. Tissue injury: edema in lung and heart. Larsen et al., 2010 [65 ] TiO2 (28) Intraperitoneal injections : immunization with 1 μ g OVA alone or in combination with either 2, 10, 50 or 250 μ g TiO2 .7-8 inbred female BALB/cJ mice per group OVA-specific antibodies in serum: TiO2 increased IgE and IgG1 levels compared to the OVA-controls. Inflammatory action: EOSs, NEUs, LYMs, IL-4, and IL-5 increased in BAL.Hamilton et al., 2009 [37 ] Anatase TiO2 nanospheres (60 ~ 200) 2 long nanobelts (width: 60 ~ 300 nm; length 15 ~ 30 nm) 2 short nanobelts (width: 60 ~ 300; length 0.8–4 μ m) Pharyngeal aspiration : 30 μ g/mouse TiO2 .Male C57BL/6 mice Inflammatory action: cathepsins, IL-1β , IL-18 increased after long nanobelts aspiration. Kobayashi et al., 2009 [38 ] Anatase TiO2 (4.9) (1st and 2nd experiment) 2 (23.4) 2 (154.2) Intratracheal instillation : 5 mg/kg TiO2. 5 male Crl: CD (SD) rats per group Inflammatory action: 1st: 4.9 and 23.4 nm TiO2 NPs increased TCC, NEUs, LDH; 2nd: agglomerated TiO2 increased TCC, NEUs, LDH. Histology: epithelium hypertrophy in all treated groups. Van Ravenzwaay et al., 2009 [66 ] Anatase-rutile TiO2 mixture (20–30) 2 (200) Inhalation : aerosols of 100 and 250 mg/m3 uncoated and pigmentary TiO2 , respectively for 6 h/day on 5 consecutive days. Intravenous injections : 5 mg/kg.3–6 male Wistar rats (strain Crl:WI (Han) per group TiO2 distribution: lung and mediastinal lymph node after inhalation; mostly liver and spleen after injection. Inflammatory action: both TiO2 increased TCC, PMNs, TPC, ALP, LDH, GGT, NAG in BAL. Ma-Hock et al., 2009 [67 ] Rutile-anatase TiO2 mixture (25.1) Inhalation : aerosols of 2–50 mg/m3 TiO2 for 6 hr/day for 5 days.5-6 male Wistar rats (strain Crl: WI (Han)) per group Inflammatory action: PMNs, GGT, TPC, LDH, ALP, NAG increased in BAL. Cell replication: increased in bronchi and bronchioles. Liu et al., 2009 [36 ] Anatase TiO2 (5) 2 (21) 2 (50) Intratracheal instillation : 0.5–50 mg/kg.12 male and female Sprague Dawley rats per group Inflammatory action: LDH and ALP increased in lung by 5 and 50 nm TiO2 . Histology: inflammatory infiltration, alveolar wall thickening. AM phagocytic ability: altered by 5 and 50 nm TiO2 . Sager et al., 2008 [12 ] P25 TiO2 (21) 2 (1 μ m) Intratracheal instillation : 0.26–1.04 mg/rat for 21 nm TiO2 and 5.35–21.41 mg/rat for 1 μ m TiO2 .Male Fischer CDF (F344/DuCrl) rats Inflammatory action: both TiO2 increased PMNs, LDH, ALB, TNFα , IL-1β , MIP2. Oxidative stress: increased by both TiO2 . Sager and Castranova, 2009 [68 ] P25 TiO2 (21) Intratracheal instillation : 0.26–1.04 mg/rat TiO2 .8 male Fischer CDF (F344/DuCrl) rats per group Inflammatory action: increase in PMNs, ALB, and LDH in BAL. Park et al., 2009 [69 ] P25 TiO2 (21) Intratracheal instillation : 5, 20, 50 mg/kg TiO2 .10–12 ICR mice per group Inflammatory action : IL-1, TNF-α , IL-6, IL-12, IFN-γ , IL4, IL-5, IL-10, and IgE increased in BAL. Histology: inflammatory proteins, granulomas. Gene expression: upregulation of genes involved in antigen presentation and immune cell chemotaxis. Chen et al., 2009 [22 ] Anatase TiO2 (80–110) Intraperitoneal injections : 324–2592 mg/kg TiO2 .10 male and female ICR mice per group Histology : alveolar septal thickening and interstitial pneumonia. Moon et al., 2010 [47 ] P25 TiO2 ( 21) Intraperitoneal injections : 40 mg/kg TiO2 alone or 30 min after 5 mg/kg LPS injection.10 BALB/c mice per group Inflammatory action: NEUs, TPC; TNF-α , IL-1β , MIP2 increased by TiO2 or TiO2 + LPS. Rossi et al., 2010 [70 ] Rutile TiO2 (<5 μ m) 2 mixture (30–40) 2 (<25) 2 (~
1
0
×
4
0
) 2 /brookite (21) Inhalation:
1
0
±
2
mg/m3 TiO2 for 2 hr; 2 hr on 4 consecutive days; 2 hr on 4 consecutive days for 4 wks.8 female BALB/c/Sca mice per group Inflammatory action: NEUs in BAL, CXCL1 lung tissue, TNF-α in AMs increased by silica TiO2 . Rossi et al., 2010 [71 ] Silica coated rutile TiO2 (~10 × 40) 2 (<5 μ m) Inhalation :
1
0
±
2
mg/m3 TiO2 for 2 hr a day, 3 days a wk, for 4 wks.8 female BALB/c/Sca mice per group Inflammatory action: EOSs, LYMs, AMs, PAS+ globet cells, IL-1β , TNF-α , IL-4, -13, -10 decreased by silica TiO2 . Airway reactivity: decreased by silica TiO2 ; increased by fine TiO2 Scuri et al., 2010 [72 ] P25 Degussa TiO2 (21) Inhalation : 12 mg/m3 TiO2 for 5.6 hr a day, for 3 consecutive days.29 male and female Fischer 344 rats Neurotrophin expression: NGF, BDNF and their receptors increased in 2 day and 2 wk old rats. Airway resistance: increased in 2 wk old mice. Li et al., 2010 [73 ] Anatase TiO2 (3) Intratracheal instillation: 3.3 mg/kg TiO2 once a wk for 4 wks.13 male Kunming mice per group Inflammatory action: ACP, ALP increased in BAL. Histology: destroyed alveolar walls. Liu et al., 2010 [74 ] TiO2 (5) 2 (200) Intratracheal instillation: 0.5–50 mg/kg TiO2 3 male and 3 female Sprague-Dawley rats per group AM phagocytic and chemotactic ability: reduced by TiO2 NPs. Tang et al., 2010 [75 ] TiO2 (5) Intratracheal instillation: 0.8–20 mg/kg TiO2 .8 male Sprague Dawley rats per group TiO2 NP aggregation: present in lung at the lowest doses. Histology: lung gaps expanded, hyperemiaTang et al., 2011 [40 ] Anatase TiO2 (5±1) Intratracheal instillation: 0.8–20 mg/kg TiO2 .8 male Sprague Dawley rats per group Histology: AM increase, lung gaps expanded, hyperemia, alveolar thickness. Cho et al., 2010 [32 ] TiO2 (30–40) Intratracheal instillation: 50 and 150 cm2 /rat5 female Wistar rats per group Inflammatory action in BAL and histology of the lung : no effect. Leppanen et al., 2011 [76 ] Anatase + Brookite TiO2 (20 nm) Inhalation: 8– 30 mg/m3 for 0.5 hr (acute exposure); 30 mg/m3 for 1 hr a day, 4 days a wk for 4 wks (sub-chronic exposure)4–6 male Crl:OF1 mice per group Airflow limitation effect: reduction in expiratory flow in all the exposure situations. Inflammatory action: no effectMorimoto et al., 2011 [46 ] Rutile TiO2 (35) Inhalation :
2
.
8
±
0
.
9
×
1
0
5
/cm3 6 hr a day for 4 wks.30 male Wistar rats per group Inflammatory action: no effect. Hougaard et al., 2010 [77 ] Rutile UV-titan L181, modified with Zr, Si, Al and coated with polyalcohols (
2
0
.
6
±
0
.
3
) Inhalation:
4
2
.
4
±
2
.
9
TiO2 mg/m3 for 1 hr a day, for 11 gestational consecutive days.Female time-mated C57BL/6BomTac mice Inflammatory action: increased NEUs, and LYMs, decreased AMs in BAL. Halappanavar et al., 2011 [78 ] See Hougaard et al., 2010 [77 ] Inflammatory action: TiO2 increased mRNA for Saa1, Saa3, several C-X-C and C-C motif chemokines, TNF-α . Nemmar et al., 2011 [79 ] Rutile Fe-doped nanorod TiO2 (length: 80; diameter: 7) Intratracheal instillation: 1,5 mg/kg TiO2 4 male Wistar rats per group Inflammatory action: NEUs, IL-6 increased, SOD activity decreased in BAL. Histology: inflammatory cell infiltration. Hussain et al., 2011 [80 ] Anatase TiO2 (15) Oropharyngeal aspiration : ~0.8 mg/kg TiO2 5-6 male BALB/c mice Airway reactivity: increased by TiO2 in TDI sensitized mice Inflammatory action: TiO2 increased NEUs and AMs in BAL of TDI sensitized mice. Gustafsson et al., 2011 [48 ] P25 Degussa TiO2 Intratracheal instillation: 1, 5, and 7.5 mg/kg TiO2 5–20 male Dark Agouti rats per group Inflammatory action : transient increase in EOSs and NEUs in BAL, followed by a recruitment of DCs and NKs. Elevated levels of IL-1, IL-2, IL-6, CINC-1, and GM-CSF.
